There have, in recent years, been a number of important developments in the field of paving extending the range of options available for materials and finishes and the way in which the paving is laid. One of the most important developments was the introduction of pattern-imprinted concrete to enable an area of paving to be given the appearance of block paving when, in fact, it is formed in situ as a layer of concrete is subsequently coloured and imprinted using a set of moulds for the pattern design, pressed down from above. An example of this system is described in GB 2,193,989A. Among benefits that can be obtained from this process is the ability to obtain a block paved appearance with a substantially monolithic formation that stops through-growth of weeds. Furthermore, the paving can be laid comparatively rapidly and less labour intensively than conventional block paving. However, the level of skill required to lay the pattern imprinted concrete paving is substantially higher than for block paving and there are tight constraints in when and how the pattern-imprinted concrete can be laid.
Laying pattern-imprinted concrete during hot periods should be avoided to prevent accelerated concrete curing which can lead to crack formation. The quality of the installation during hot spells can also be undermined as the installers are under greater pressure to rush the process before the concrete is too hard to work with, i.e. loss of pattern definition.
Given constraints such as the finite curing time window, the need to pattern imprint substantially the full area to be paved in one session in order to avoid unsightly discontinuities in the pattern, to ensure the colour is consistant throughout and the difficulty in rectifying any errors once the pattern has been applied, speed, care and skill are all needed. Luck with the weather also helps. As with any process based on curing of cement/concrete, and especially with coloured pattern-imprinted concrete, if not sheltered a sudden downpour could be disastrous, affecting the colour and imprint if the concrete had not hardened sufficiently or the job was still in progress at any stage.
Therefore climatic conditions have a great bearing on the outcome of pattern imprinted concrete quality, which deters many block paving and paving companies from getting involved as this could lead to jobs being excavated and relaid.
Furthermore, although the monolithic construction gives one of the key benefits of pattern-imprinted concrete, some provision still has to be made for concrete expansion and contraction during varying weather conditions and possible slight ground movement, by including expansion and contraction joints or crack control joints (gap) in the formation. These are generally placed at certain intervals at the discretion of the installer and can in some patterns appear unsightly. Placing of these joints is no guarantee that cracks are prevented, as has happened on many occasions.
It is a general objective of the present invention to provide an improved paving system which exploits benefits of the existing pattern-imprinted concrete systems, while increasing the ease with which they can be laid, reducing the skill levels necessary.
It is an objective to mitigate against the need for visible expansion lines and enable the paving to be built up in manageable modular regions without undermining the integrity or the appearance of the paving. It is a further objective to enable good access to be had to remote areas of the paving being laid before the concrete has cured.
It is a further general object to make the system economical to implement, and in combination with the reduction in skill required, to enable a pattern-imprinted concrete type of approach to be used far more widely as an alternative to the conventional cobble-laying, block paving, slabs or tarmacing of driveways, patios and other paved areas in domestic and commercial premises.
It is an objective to be able to lay paving imitating the look of pattern imprinted concrete in hot or inclement weather conditions reducing downtime, whilst maintaining quality.
It is an objective to prevent cracking throughout the installation by providing a system that facilitates movement, expansion and contraction.
It is an objective to facilitate better access to the client into their home by boards placed over the area being paved, a difficulty with normal pattern imprinted concrete paving during the setting period.